The desktop’s Redhat, and the image viewer is “xvd”, an in-house tool for viewing images in the raw, uncompressed VICAR format.
Source: I work in JPL’s MIPL
EDIT: And also, fun fact, there’s another in-house tool that’s used to display the uncompressed images alongside its metadata. They decided to not use it last minute because it didn’t perform Image stretching, and they wanted the first image to be in color.
NASA and Debian
“We migrated key functions from Windows to Linux because we needed an operating system that was stable and reliable.”